Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: Davenotdone on November 06, 2012, 05:07:47 pm

Title: Hydro Prop.
Post by: Davenotdone on November 06, 2012, 05:07:47 pm

Could somebody please tell me the difference between a ' normal ' two bladed plastic 30mm plastic prop and a ' hydro ' two bladed plastic prop? The reason is i have converted a ready to run cheap police boat appox 22 inches long, V shaped hull, Graupner Speed 400 ( 7.2v version ) running off a 7.2v stick battery. The speed is quite good but the motor felt a bit warm / hot. I only noticed after that i was sold a Hydro prop so does this make any difference?

Title: Re: Hydro Prop.
Post by: DickyD on November 06, 2012, 05:29:38 pm

The less pitch on the blades the cooler the motor.


Also will often give more speed.  (http://i124.photobucket.com/albums/p8/DickyD_photos/Smileys/tumb.gif)

Title: Re: Hydro Prop.
Post by: Davenotdone on November 06, 2012, 09:19:02 pm

Thanks for that but do Hydro props have more pitch or less than a normal prop. Shall i get a new normal 30mm prop or drop down to say a 26mm one? All suggestions welcome please, i am a bit new to all this. I don't need all out speed, i would rather have reasonable speed and a longer run time. If you need to know the stick battery is 7.2v 5000mah. Regards, Dave.

Title: Re: Hydro Prop.
Post by: grasshopper on November 06, 2012, 09:37:32 pm

Standard props (p) will have less pitch than racing (x) props and usually hydro or surface (s) have even greater pitch than racing. Blade shape and profile also make a difference.


For a 400 motor on 7.2 volts a 30 mm hydro prop' run submerged will warm the motor quite quickly. Go for an X and then down to a 26mm to see which gives you the performance you want.

Title: Re: Hydro Prop.
Post by: Davenotdone on November 07, 2012, 06:02:45 am

Thanks to you all for your help, i have decided to go for a Graupner racing type 2 blade plastic prop of 25mm ( part No G451.0 )  to see if that works better. Bit new to all this but hope to post pictures of 2 converted RTR boats i am building / converting  ( this one which is a Police type and a Seaport Dickie tug ) The Dickie is now on it's 3rd motor!!!!    Regards, Dave.

Title: Re: Hydro Prop.
Post by: DickyD on November 07, 2012, 06:15:49 am

I personally would have gone for a fine pitch 30mm 2blade first.


What have you done to the Dickie tug, I have a converted one which I did several years ago and it still has its original motor ?


(http://i124.photobucket.com/albums/p8/DickyD_photos/The%20Fleet/DSCF2093-Copy.jpg)

Title: Re: Hydro Prop.
Post by: martno1fan on November 07, 2012, 08:27:04 am

Hi a hydro prop usually has more lift,this is needed on hydros as theyre suposed to run on the prop and a hydro hull has zero hull touching the water at the transom.
Hydro props or high lift props are not usually a good choice on a mono hull hope this helps some.
Mart

Title: Re: Hydro Prop.
Post by: Davenotdone on November 11, 2012, 08:42:15 pm

Thanks to you all for your advice, could you suggest a 30mm fine pitch 2 blade( 4mm shaft ) prop please? Regards, Dave.